The X-ray system is employed for a number of purposes such as medical use (diagnosis/treatment), industrial non-destructive inspection, and material analysis. An X-ray tube used in the X-ray system is configured to make an electron beam from a cathode filament collide with an anode target and to generate X-rays.
The X-ray tube obtains thermoelectron which is an origin of a tube current, which corresponds to an electron beam colliding with a target, from heating of the filament. Heating the filament is executed by making an appropriate current flow to the filament. If a thermoelectron emission power (emission) of the filament is lowered or the degree of vacuum in a vacuum tube is lowered due to accumulation of an actual time of use of the X-ray tube, the tube current is reduced to the outside of the appropriate range and necessary X-ray output cannot be obtained.
An automatic X-ray tube calibration system for monitoring the tube current and controlling the filament current and a power consumption monitoring system for detecting X-ray irradiation abnormality have been conventionally present. However, these systems do not have a function of inspecting a relationship between the tube current and the filament current to be within an appropriate range.